The contact conductance of copper based brush thermal connections were investigated. Results show a significant increase in heat transfer as compared to purely radiative connections during a cool down from +20 °C to -180 °C. Derived contact conductance values are higher than for common slip-rings or ball bearings.
Two possible applications initiated the interest for copper based brushes. First there are science instrument designs with moving carousels and low temperature requirements which could be cooled down by cryo-coolers. Here brushes could close the connective link in certain positions of the carousel, using the already present motorisation of the carousel in order to avoid further mechanisms. A second application is the increase in cool down velocity when moving from a purely radiative to a conductively supported cool down in a test facility for fast thermal cycling over a very wide temperature range.
Conductive links between moving and static components are always associated with large uncertainties in thermal analysis. Thus, in order to reduce this modelling uncertainty, a test set-up was designed to test the conductive link of a custom copper based brush and eventually compare it to similar conductive links such as rotor-stator interactions in slip-rings or ball bearing contacts.